Preliminary genome-wide association study of bipolar disorder in the Japanese population.

Recent progress in genotyping technology and the development of public databases has enabled large-scale genome-wide association tests with diseases. We performed a two-stage genome-wide association study (GWAS) of bipolar disorder (BD) in Japanese cohorts. First we used Affymetrix 100K GeneChip arrays in the analysis of 107 cases with bipolar I disorder and 107 controls, and selected markers that were nominally significant (P < 0.01) in at least one of the three models (1,577 markers in total). In the follow-up stage, we analyzed these markers using an Illumina platform (1,526 markers; 51 markers were not designable for the platform) and an independent sample set, which consisted of 395 cases (bipolar I + II) and 409 controls. We also assessed the population stratification of current samples using principal components analysis. After the two-stage analysis, 89 markers remained nominally significant (allelic P < 0.05) with the same allele being consistently over-represented in both the first and the follow-up stages. However, none of these were significant after correction for multiple-testing by false discovery rates. Sample stratification was virtually negligible. Collectively, this is the first GWAS of BD in the Japanese population. But given the small sample size and the limited genomic coverage, these results should be taken as preliminary.

Selective serotonin reuptake inhibitors, fluoxetine and paroxetine, attenuate the expression of the established behavioral sensitization induced by methamphetamine.

To obtain an insight into the development of a new pharmacotherapy that prevents the treatment-resistant relapse of psychostimulant-induced psychosis and schizophrenia, we have investigated in the mouse the effects of selective serotonin reuptake inhibitors (SSRI), fluoxetine (FLX) and paroxetine (PRX), on the established sensitization induced by methamphetamine (MAP), a model of the relapse of these psychoses, because the modifications of the brain serotonergic transmission have been reported to antagonize the sensitization phenomenon. In agreement with previous reports, repeated MAP treatment (1.0 mg/kg a day, subcutaneously (s.c.)) for 10 days induced a long-lasting enhancement of the increasing effects of a challenge dose of MAP (0.24 mg/kg, s.c.) on motor activity on day 12 or 29 of withdrawal. The daily injection of FLX (10 mg/kg, s.c.) or PRX (8 mg/kg, s.c.) from 12 to 16 days of withdrawal of repeated MAP administration markedly attenuated the ability of the MAP pretreatment to augment the motor responses to the challenge dose of the stimulant 13 days after the SSRI injection. The repeated treatment with FLX or PRX alone failed to affect the motor stimulation following the challenge of saline and MAP 13 days later. These results suggest that the intermittent and repetitive elevation of serotonergic tone may inhibit the expression of the motor sensitization induced by pretreatment with MAP. It is proposed that clinically available serotonin reuptake inhibitors could be useful for preventing the recurrence of hallucinatory-paranoid state in drug-induced psychosis and schizophrenia.

Effects of schizophrenomimetics on the expression of the CCN1 (CYR 61) gene encoding a matricellular protein in the infant and adult neocortex of the mouse and rat.

The acute systemic administration of a schizophrenomimetic phencyclidine [5 or 10 mg/kg, subcutaneously (s.c.)] markedly up-regulated the neocortical expression of the CCN1 gene encoding a secreted extracellular matrix-associated protein at postnatal day 56, but not at postnatal day 8, after 60 min in the mouse and rat. The development-dependent nature of the up-regulation between postnatal days 8 and 56 seems to be similar to that of the adult type phencyclidine-induced abnormal behaviours, which have been considered to be models of schizophrenic symptoms. In the young adult rat, 5, 10, and 20 mg/kg phencyclidine (given s.c.) induced an increase in the CCN1 gene transcripts in a dose-related and bell-shaped manner with a maximum at the dose of 10 mg/kg, 60 min post-injection. Other schizophrenomimetics, dizocilpine (1 mg/kg) and methamphetamine (4.8 mg/kg), also caused a prominent up-regulation of the neocortical expression of the CCN1 gene in adult rats. These results indicate that the CCN1 gene or protein could be implicated in a molecular cascade associated with the age-dependent onset of schizophrenia that usually occurs after puberty.